Ceramic pedestals are useful in applications in which processing temperatures are too high for aluminum pedestals to withstand. One such application is the deposition of ashable hardmasks (AHMs). AHMs are films used in semiconductor processing that may be removed by a technique referred to as “ashing.” In particular, AHMs are often used as etch stop layers. 193 nm or lower lithography schemes require these AHMs to have high etch selectivity to underlying dielectric or metal barrier layers. In addition, 193 nm lithography schemes employ a 633 nm mask alignment laser—requiring the AHM to be transparent to light at 633 nm.
Current methods of producing highly selective AHMs rely on relatively high temperature (greater than 500 C) PECVD deposition processes. At these temperatures, dense films rich carbon are deposited. These conventional processes operate at pressures as high as 6-10 Torr—pressures at which many PECVD reactors are not designed to withstand. In addition, the extinction coefficient (“k value”) of these films is higher than ideal for 193 nm lithography schemes.